One of the Facebook engineers said the new application has been built primarily using Objective-C, the programming language used to build applications for iOS. Many of the components of the current version of the Facebook app are built using HTML5, the Web-based markup language.

This is really welcome news. The Facebook app on iOS today is awful. A rewrite using native code (rather than a mixture of Objective-C and webviews) is greatly needed.1

1 Maybe Apple pressured them to do this, as part of the negotiations surrounding Facebook integration into iOS 6?